I Have Arthritis And I Want To Know What Tests My Rheumatologist Is Going To Order

are a number of laboratory tests that apresent with arthritis, a CPK is a good test to order.
rheumatologist may order when seeing a patient forThyroid function tests. Thyroid disease often is
the first time. This is particularly true if rheumatoidpresent in patients with inflammatory arthritis. It is
arthritis (RA) is suspected. The reason so manybecause autoimmunity seems to be involved in the
laboratory tests are needed is because of thedevelopment of both of these problems. An
complexity involved in arriving at the correctunderactive thyroid (hypothyroidism) can also cause
diagnosis. Oftentimes, diseases can look similar.aches and pains and “muddy the diagnostic
Disease may evolve over time and sometimes theywaters”. With severe thyroid disease,
overlap.elevations in CPK may be seen.
The following is a rundown of the different testsComplete Blood Cell Count (CBC). Chronic
that can be ordered and why.inflammation can lead to an anemia. This is a common
Erythrocyte Sedimentation Rate (ESR). This test-alsooccurrence in patients with rheumatoid arthritis. Also,
known as the “sed rate” measuressome of the non-steroidal anti-inflammatory drugs
how fast the red blood cells settle to the bottom of(NSAIDS) which patients with RA take can cause
a tube in 1 hour. Inflammation causes the red cells toulcers which can lead to blood loss. Also, a low white
clump together and therefore settle faster. The rateblood cell count may be a sign of drug toxicity or
in normal individuals is up to 20 mm in 1 hour.another disease process such as lupus. Also, it is
Inflammation increases this rate so that a patientgood to have a baseline result to help with drug
with a disorder such as active rheumatoid arthritis willmonitoring
often have a sed rate much higher than 20mm.Chemistry Panel. Viral hepatitis can present with
C-Reactive Protein (CRP). CRP measures a proteininflamed joints. It is important to make sure that liver
produced by the liver that is present during acutefunction test results are normal. It is a good idea to
inflammation or infection. The CRP test can be usedhave a baseline in case potentially liver damaging
to monitor the effectiveness of treatment as well asmedications such as non-steroidal anti-inflammatory
to monitor disease flares.drugs or methotrexate are used. Another organ
Both of these tests correlate with x-ray damage duesystem, the kidney can also be affected not only by
to RA and long-term disability; persistent elevationsdiseases such as lupus or Sjogren’s disease
of these blood markers suggest a poor prognosis.but also is a target for drug toxicity. NSAIDS are the
ESR is usually elevated in inflammatory arthritis, butchief culprits. Also, if a patient’s kidney
can be less useful than the CRP, because the ESRfunction isn’t normal it will affect the rate of
rises more slowly and falls to normal more slowlyelimination of some drugs that are used to treat
once inflammation is controlled. The CRP tends to riserheumatoid arthritis. Drug toxicity then becomes an
faster and go down faster than the sed rate inissue.
response to inflammation. Also, in very earlyViral Hepatitis Panel. As mentioned above, viral
inflammatory disease, both the ESR and CRP mayhepatitis can present with an inflammatory form of
not be elevated, so normal levels do not rule out thearthritis. Prior to starting any medicine that can
presence of significant disease. These tests areadversely affect the liver, it is important to have a
essential to get at baseline, because there isbaseline in regard to chronic hepatitis B and C
evidence they may be useful in predicting diseaseinfections. Before using anti-TNF medications and
severity or response to therapy.rituximab (Rituxan), the rheumatologist must check
Rheumatoid Factor (RF). RF is an immunoglobulin. It ishepatitis status, especially in regards to hepatitis B
in the IgM category of antibodies and is directedbecause these drugs can cause aggravation of
against another type of antibody type called IgG. It ishepatitis B.
present in about 70% of patients with RA.Urinalysis. A urine sample is studied for protein, red
Unfortunately, an elevated level of RF can be seen inblood cells, white blood cells, or casts. These
about 10% of normal people. Additionally, in roughlyabnormalities may indicate kidney damage due to
20% of patients with RA, the RF is not elevated,lupus or vasculitis. Use of some medications, because
and so a negative test result does not rule out RAthey can injure the kidneys, require initial as well as
as a cause of the patient's symptoms. The presenceongoing screening for urinary abnormalities.
of RF correlates with aggressive and erosive disease.Complement levels. Complement is a serum protein
And high levels of RF appear to suggest a worsethat is important in the assessment and monitoring of
prognosis. RF can take months to develop, and somedifferent types of autoimmune disease. Lowered
RA patients remain negative for RF throughout thelevels of complement (C3, C4) are indicative of
course of their illness.immune complex formation (where an antibody binds
Other autoimmune diseases that can be associatedto an antigen- a foreign protein) and complement
with a positive RF include systemic lupusbinding. Lupus patients often show decreased levels
erythematosus, Sjogren’s disease,of total complement, which may be helpful in tracking
polymyositis, dermatomyositis, scleroderma, anddisease activity.
mixed connective tissue disease. Infections and otherX-rays. X-rays of hands, wrists, feet, and knees are
diseases can also be associated with a positive RF.useful for detecting the presence of erosions. If
These include sarcoidosis, tuberculosis,endocarditis,erosions are seen, especially in early disease, this
hepatitis (especially hepatitis C), syphilis, osteomyelitis,suggests the diagnosis of RA or other erosive
infectious mononucleosis, and cirrhosis. A positive RFdiseases, and can indicate a more aggressive disease
would not usually be seen in types of arthritis such asprocess.
gout, osteoarthritis, ankylosing spondylitis, andMagnetic Resonance Imaging (MRI). MRI is more
psoriatic arthritis,.sensitive than x-rays for detecting inflammation
Anticyclic Citrullinated Peptide Antibody (anti-CCP).within the joint and also for detecting early erosions
This is a relatively new blood test thaqt helps toin RA.
confirm a diagnosis of RA. Anti-CCP appears to beDiagnostic Ultrasound (DUS). Ultrasound is a relatively
more specific for RA. Anti-CCP antibody is present innew technology in the realm of musculoskeletal
approximately 30% of RF negative RA (seronegativediseases. It is an effective, fast, and cost-effective
RA). Testing with the combination of anti-CCPmeans of detecting early inflammation and damage in
antibody and RF may be better for ruling out RApatients with different types of arthritis.
than using either test alone.Chest X-ray. A chest x-ray (CXR) in patients with
High levels of anti-CCP are seen in severe andearly RA will likely be normal. However, because
progressive disease.RA-related lung disease can be present early and
Antinuclear Antibody (ANA). The ANA test can helpmay be difficult to detect on physical exam, it is
detect SLE. However, an elevated ANA is notreasonable to obtain a baseline CXR to evaluate if
specific, and can be seen in disorders other thansigns of lung disease are present. In addition, because
lupus, including a significant percentage of patientssome agents, such as methotrexate and anti-TNF
with RA. More than 95% of patients with lupus havedrugs, which are used to treat RA can lead to lung
a positive ANA test. A more specific test for SLE istoxicity, getting a baseline CXR before starting
the presence of antibodies to DNA (anti-DNA). It ismedication therapy is reasonable.
unusual to find antibodies to DNA (anti-DNA) in peopleNot all of the above tests will necessarily be ordered
who do not have lupus. Levels of anti-DNA vary withat the first visit. But this is a good basic list that will
disease activity.give the reader a good idea of what to expect.
Antibodies to Sm, RNP, Ro (SSA), La (SSB). LupusAnother issue is the laboratory. If the rheumatologist
patients also have other antibodies to different cellhas his or her own specialty laboratory and it is
nuclear components. Antibodies to Sm occur only instate-certified as a reference lab, I would highly
patients with lupus while antibodies to RNP occur inrecommend that a patient get their lab tests done at
patients with mixed connective tissue disease, andthat office. A rheumatologist will have the best idea
antibodies to Ro and La may occur in patients withas to lab test interpretation and the
Sjogren’s disease.rheumatologist’s lab will be experienced in
Creatine phosphokinase (CPK). CPK is a muscledealing with arthritis. They will provide the most
enzyme that is elevated in a number of types ofaccurate and believable results. All too often, large
inflammatory conditions, particularly inflammatorycommercial labs are not used to dealing with the
muscle diseases such as polymyositis andcomplexity of arthritis testing. A correct diagnosis is
dermatomyosotis. Since these conditions can alsokey!